The invention relates to the ovine embryo cell line HVO-156 (DSM ACC2440), or to cell lines derived therefrom, and to their use for preparing and propagating ovine adenoviruses, in particular recombinant ovine adenoviruses which are derived from the isolate OAV 287.
Genetic defects can cause diseases, such as cancer, cystic fibrosis, muscular dystrophy and others. A large number of gene therapy methods have already been proposed for remedying these genetic defects. Methods for preparing vectors which are able to introduce therapeutic genes into the genetically defective target cells with an adequately high efficiency constitute the basis for a successful gene therapy.
The ability of viruses, which is highly developed from the evolutionary point of view, to introduce genetic material into mammalian cells suggests that viral vectors should be used for gene therapy. Thus far, it is first and foremost human viruses having low pathogenic potential, such as attenuated adenoviruses, adenoassociated viruses, herpesviruses and retroviruses, which have been employed as vectors. In connection with this, it has been recognized that none of the systems mentioned can be used for any gene therapy applications. In general, an immunity which preexists endemically in most people, and which was elicited by an infection with these viruses in childhood, suggests that it will not be possible to use human viral vectors successfully in humans.
Viral vectors which are able to overcome this preexisting immunity in humans are based, inter alia, on ovine adenoviruses, in particular the ovine adenovirus isolate OAV 287. This virus, and the use of recombinant variants of the virus for gene therapy, is described in WO96/03508 and WO97/06826. However, problems have thus far been associated with preparing and propagating viruses of this nature. The ovine lung cell line CSL 503 (Pye et al., Austr. Vet. J. 66: 231-232 (1989)), which is at present the only cell line available for this purpose, is not particularly efficient. Thus, only a small number of recombinant ovine adenoviruses are formed when this cell line is transfected with recombinant ovine adenovirus DNA. In addition to this, the cell line CSL 503 only has a relatively short life span of what is normally less than 20 passages and therefore only allows viruses to be replicated at a comparatively low rate.
There therefore exists a need to provide alternative cell lines which have a higher efficiency for preparing adenoviruses. It has been found that ovine embryo cell lines, in particular the ovine embryo cell line HVO-156 (DSM ACC2440), or cell lines derived therefrom, enable adenoviruses to be propagated with such a degree of efficiency. These cells are distinguished by a long life span (the ability to be passaged at least 40 times, corresponding to  greater than 100 generations), the ability to be readily transfected with recombinant DNA, a high degree of efficiency in the formation of recombinant ovine adenoviruses and a high rate of propagation of recombinant ovine adenoviruses.
The invention consequently relates to the ovine embryo cell line HVO-156 (DSM ACC2440) or to a cell line which is derived therefrom. This cell line was deposited in the DSMZ (Deutsche Sammlung von Mikroorganismen und Zellkulturen GmbH [German collection of microorganisms and cell cultures GmbH]), Mascheroder Weg 1b, D-38124, Braunschweig, in accordance with the provisions of the Budapest treaty, on Dec. 22, 1999.
The deposited cell line, or cell lines which are derived therefrom, for example by subcloning, and also other ovine embryo cell lines, are suitable for preparing and/or propagating adenoviruses, in particular ovine adenoviruses, such as ovine adenoviruses of the isolate OAV 287 and recombinant viruses which are derived therefrom.